Establishment of a seal between concentric surfaces in a high temperature environment

ABSTRACT

A valve comprising a valve body having a central portion in which a ball is rotatably mounted, a tubular extension welded to each side of the central portion, and an annular seat mounted in the flowway through each tubular extension. In the assembly of the valve, the seat is mounted within the flowway during welding of the extension to the central portion of the body. There is a groove in the flowway about each valve seat, and a sealing ring is carried within each groove. The ring is of a material such as Teflon which, if confined against expansion while heated due to its proximity to the weld between the body portions, would reform into a different, nonsealing shape when cooled to ambient temperature. The base of the groove is deeper at one end than at the other and wider than the seal ring, so that said ring is relatively loosely received within the deeper end of the groove and relatively tightly engaged between the seat and the shallower end of the groove. The seal ring is arranged within the deeper end of the groove during welding and then moved into the shallower end thereof when the ring is cooled.

United States Patent [72] Inventor Frank V. Ellis Houston, Tex.

[2]] Appl. No. 778,283

[22] Filed Nov. 22, 1968 [45] Patented Apr. 20, 1971 [73] AssigneeCameron Iron Works, Inc.

Houston, Tex.

[54] ESTABLISHMENT OF A SEAL BETWEEN CONCENTRIC SURFACES IN A HIGH [56]References Cited UNITED STATES PATENTS 2,747,600 5/1956 Laurent 251/1722,992,028 7/1961 Knox 277/1 3,069,763 12/ 1 962 Reynolds 29/488 PrimaryExaminer-William F. ODea Assistant Examiner-David R. MatthewsAtt0rneyHyer, Eickenroht and Thompson & Turner ABSTRACT: A valvecomprising a valve body having a central portion in which a ball isrotatably mounted, a tubular extension welded to each side of thecentral portion, and an annular seat mounted in the flowway through eachtubular extension. In the assembly of the valve, the seat is mountedwithin the flowway during welding of the extension to the centralportion of the body. There is a groove in the flowway about each valveseat, and a sealing ring is carried within each groove. The. ring is ofa material such as Teflon which, if confined against expansion whileheated due to its proximity to the weld between the body portions, wouldreform into a difierent, nonsealing shape when cooled to ambienttemperature. The base of the groove is deeper at one end than at theother and wider than the seal ring, so that said ring is relativelyloosely received within the deeper end of the groove and relativelytightly engaged between the seat and the shallower end of the groove.The seal ring is arranged within the deeper end of the groove duringwelding and then moved into the shallower end thereof when the ring iscooled.

a ll ESTABLIISNT F A SEAL BETWEEN CONCENTRIC SUNIFNCES'W A TEMPERAENVIRONMENT This'invention relates generally to improved apparatus inwhich a ring of deformable material is carried within a groove about onemember for establishing a seal with such member and the oppositelyfacing surface of another member concentric thereto under hightemperature conditions. It also relates to an improved method ofestablishing such a seal. In one of its aspects, this invention relatesto a valve in which such a ring is carried in a groove for sealing witha valve seat and a flowway through the valve body in which the seat ismounted, and to a method for assembling such a valve, and particularly amethod establishing the seal between the seat and flowway in a hightemperature environment.

Polytetrafluoroethylene, which is supplied by E, l. duPont de Nemours &Co., Inc. under the trademark Teflon, has many characteristics whichmake it well suited for use as a seal ring, especially when there isrelative movement between the members to be sealed. Thus, this material,as well as similar materials such as Kel-F and nylon, are not only inertinsofar as most fluids are concerned, butalso have low coefficients offriction with metal. Consequently, such a material is frequently used invalves and other apparatus which may contain fluids detrimental toordinary rubber seal rings, and especially as a seal ring between a seatmounted within the flowway of a valve body for relative movement withrespect thereto.

However, such materials have coefficients of thermal expansion of theorder of ten times those of the metal from which the valve body or otherapparatus is made. When a ring thereof is confined by such metal againstexpansion and then heated sufficiently high, the disparity in expansionrates causes a force to be exerted on the ring to reform it into adifferent shape on cooling. Thus, the ring may not seal or may provideonly an unreliable, leaky seal when confined by a groove betweenconcentric members in a conventional manner.

In the valve illustrated in U.S. Pat. No. 3,388,715, a seal ring iscarried between each seat and the flowway through the valve body nearportions of the body which are welded together during assembly of thevalve and while the seats are mounted within the flowway. In this valve,each seat is not only movable axially of the seat, but also rotatabletherein, so that a seal rirg of Teflon or the like is especiallyadvantageous. However, due to its proximity to the area of the weldingand its confinement within a conventional groove in the flowway, such aring would, upon cooling, reform into a different shape which would notprovide a good seal.

An object of this invention is to provide apparatus including a ring ofTeflon or like material for sealing between concentric surfaces in whichthe above-noted problems are overcome, despite the assembly of suchapparatus in an environment in which the ring is raised to a hightemperature.

Another object is to provide such apparatus in which the sealing ring isarranged between a valve seat and the flowway through the body of avalve of the type above described.

These and other objects are accomplished, in accordance with theillustrated embodiment of the present invention, by apparatus in whichthe groove in one such concentric surface is wider than the sed ring anddeeper at one end of the base of the groove than at the other endthereof. The ring is relatively loosely received in the deeper end ofthe groove and relatively tightly received between the base at theshallower end of the groove and the other concentric surface. Duringheating of the ring, it is arranged within the deeper end of the groove;and then, when the ring is cooled, it is caused to move into theshallower end of the groove to seal with the base of the groove and theother concentric surface.

In a valve of the construction above described, the groove is formedabout the flowway and the seal ring is arranged within its deeper endduring welding of the body parts. Then, upon completion of the weldingand cooling of the ring, it is moved into the shallower end of thegroove to seal with the seat and flowway.

In the drawings, wherein like reference characters are used 7 throughoutto designate like parts:

FIG. 1 is a longitudinal sectional view of a valve of the constructionabove described;

FIG. 2 is an enlarged sectional view of part of the valve of FIG. 1, butwith the closure member moved to flowway closing position, and showingan illustrative embodiment of a seal arrangement constructed inaccordance with the present invention for sealing with the flowway and aseat mounted within the flowway;

FIG. 3A is a further enlarged cross-sectional view of the seal ring ofsuch seal arrangement removed from between the seat and flowway;

FIG. 3B is a detailed view of the seal ring of FIG. 3A, but upondisposal thereof between the deeper end of the groove in the flowway andthe valve seat; and

FIG. 3C is a view similar to FIG. 3B, but with the seal ring urged intotight sealing engagement with the shallower end of the groove and thevalve seat.

With reference to the details of the above-described drawings, the valveshown in FIG. I, and designated in its entirety by'reference character10, includes a metallic valve body 11 having a flowway l2 therethroughand a closure member 13 movable within the body for opening'and closingthe flowway. The closure member 13 includes an opening 14 through a ball15 and upper and lower stems 16 and 17, respectively, to rotate itbetween flowway open and closing positions.

The valve body 11 includes a central portion 18 having bearings 19 and20 on the upper and lower sides thereof, respectively, for receiving theball stems l6 and 17. Stem 16 extends through the bearing 19 to providean external part for actuating the closure member. The inner surface ofthis central body portion is shaped spherically and concentrically ofthe outer surface of ball 15 to provide a cavity fitting closelythereabout.

The valve body 11 also includes tubular extensions 21 connected byweldment 22 to the opening in each opposite end of central body portion18. These tubular extensions have flanges 23 on their outer ends forconnecting the valve in a pipeline and annular recesses 24 on theirinner ends adjacent the closure member 13 to form enlarged diameterportions of the flowway 12 for receiving seats 25 adapted to sealagainst opposite sides of the closure member in the closed positionthereof.

As described more fully in US. Pat. No. 3,157,190, the central portion18 of the valve body 11 may be split along a plane passing through theaxis of the flowway and perpendicular to the axis of rotation of theclosure member, and the split parts then assembled over the stems l6 and17 and welded to one another to capture the closing member. Seats 25together with their associated parts, described below, are thenassembled within the recesses 24 of each tubular extension 21, and theextensions and the seats moved into positions for forming the welds 22.

In its preferred form, the valve 10 also includes a means for rotatingeach seat 25 about its axis in response to operation of the valve so asto distribute ware about the seat. Thus, as

shown in FIG. 1, a dog 27 is carried on each upper side of the ball 15for engaging with and disengaging from teeth 28'about the periphery ofthe seat 25 as the closure member is rotated between opened and closedpositions. A detailed explanation of the construction and operation ofthese parts can be found in the aforementioned US. Pat. No. 3,157,190.It will be understood that the problem toward which the presentinvention is directed is particularly important to this case, where theseat is mounted not only for reciprocation but also for rotation.

As best shown in FIG. 2, each seat 25 comprises an annular onepiece body29 having a groove 30 in its inner end for disposal opposite the closuremember -13. This groove is adapted to contain a viscous grease toprovide a sealing film across the oppositely disposed surface of theclosure member. For this purpose, the body 29 of the seat haspassageways 31 therein connecting the groove with a passageway 32 in thevalve body to which a fitting 33 is connected to permit lubricant to beinjected through the passageways and into the groove at a desiredpressure. Thus, theouter end of the valve body passageway 32 has threads34 thereabout to receive threads 35 of the fitting, which may be ofconventional construction.

A seal ring 36 of Teflon or like material surrounds the outercircumference of the seat body 29 and is carried within a groove 37about the flowway recess 24 so as to seal between the flowway and theseat body on the inner side of lubricant passageway 32, as will bedescribed below. A washer-type spring 38 engages the flowway on theouter side of the lubricant passageway 32 and the outer end of the seatbody 29 near its inner circumference. Thus, this spring not only urgesthe inner end of the seat body against the closure member 13. but alsocooperates with the seal ring 37 to enclose an annular lubricant chamberbetween the seat body and flowway with which the inner end of passageway32 and outer ends of passageways 31 are connected. As described in US.Pat. No. 3,388,715, when the pressure of the lubricant within thelubricant chamber becomes excessive, the inner end of the spring 38engageable with the outer end of the seat body disengages therefrom topennit lubricant to pass out of the chamber between the seat body andthe spring.

A washer-type spring 43 engages with flowway 12 adjacent a furtherenlarged portion 44 thereof and with an enlarged head 45 on the radiallyoutward portion of the inner end of the seat. This spring forces theseat body inwardly against the closure member and serves to preventdebris from entering the space between the flowway and seat body.

Seat also includes a seal ring 46 received with a groove about the seatbody radially outwardly from groove 30. As shown in FIG. 2, the innerend of-the ring 46 engages the outer surface of the closure member 13 toprevent lubricant from passing into the valve body downstream from theseat.

As shown in FIG. 3A, seal ring 36 is essentially C-shaped in crosssection, with legs 36a which flare outwardly when relaxed and extendtoward the pressure to be contained-Le, lubricant or line pressureupstream of the ball 13. These legs have lips 36b on the sides of theirends. Obviously, however, the ring 36 may have other cross-sectionalshapes, including O-rings.

As best shown in FIGS. 33 and 3C, base 37a of groove 37 is conical andthus deeper at the end nearer the outer end of the seat than at theother end nearer the inner end of the seat. Also, the ring 36 is wiclerthan the width of the seal ring 36. Thus, the ring shown in FIG. 2 mayoccupy a right-hand or outer position, as in FIG. 3B, in which it isrelatively loosely received within the deep end of the groove, and aleft-hand or inner position, as in FIG. 3C, in which it is relativelytightly engaged with the base 370 of the groove at its shallow end aswell as the seat body 29 for sealing therebetween.

As previously described, ring 36 is arranged in the outer position (FIG.3B) of groove 37 during welding of body portions 18 and 21. Thus, in theassembly of the valve, the seat 25 is mounted within the flowway andheld against the ball 13 prior to making of the weld. For this purpose,the ring 36 is first placed within the groove 37, and the seat isinserted into the flowway, from lefi to right in FIG. 2, which movementurges the seal ring to its outer position.

Due to the proximity of ring 36 to weld 22, the ring may be heated to700 F. or more at which it would, if confined, reform to a different,nonsealing shape upon cooling. However, since the ring is relativelyloosely received in the deeper end of the groove, it is not reformed toa nonsealing shape on cooling. Preferably, the width of groove 37 andthe taper of its conical base 37a are so proportioned that although theinner lip 36b of ring 36 is tightly engaged with seat body 29, the outerlip barely contacts-the base of the groove when in the outer position asshown in FIG. 38. Then, after movement to the inner position, the ring36 engages the base of the groove as well as the seat with a sealing,interference fit, as shown in FIG, 3C. On completion of the weldmg, andafter sufficient cooling, seal ring 36 may be moved from outer to innerposition by pressure introduced through flowway 12 and passageway 31 orthrough passageway 32.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects herein above set forth,together with other advantages which are obvious and which are inherentto the apparatus.

It will be understood that certain features and subcombinations are ofutility and may be employed with reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrative and not in a limiting sense.

Iclaim:

l. A valve, comprising a metallic valve body having a flowwaytherethrough, a closure member mounted within the body for movementbetween positions opening and closing the flowway, an annular valve seatmounted within the flowway on one side of the closure member, a grooveabout one of the flowway and valve seat opposite the annular surface ofthe other of said flowway and valve seat, and a ring within the groovefor sealing between the flowway and valve seat, said ring being formedof a material which reforms into different shape if, when raised to anelevated temperature and then cooled to ambient temperature, it isconfined against expansion, the base of the groove being deeper at oneend than at the other and wider than the seal ring, and said ring beingrelatively loosely received in the deeper end of the groove andrelatively tightly engaged between the base of the groove and saidannular surface when received in the shallower end of the groove, sothat said ring may be arranged in said deeper end when said temperatureis raised to said elevated level and then caused to move into saidshallower end when said ring is cooled to ambient temperature.

2. A valve of the character defined in claim 1, wherein said valve bodyincludes separate portions which are welded together at a location nearsaid ring.

3. A valve of the character defined in claim 2, wherein said valve bodyincludes a central portion in which the closure member is mounted andanother portion welded to and extending from one side of the centralportion, and said valve seat is mounted within a recess in the otherbody portion.

4. Apparatus comprising a first member received concentrically within asecond member, one of said members having a groove there about facingthe other member, and a seal ring within the groove which is formed of amaterial such as Teflon which reforms into a different shape if raisedto an elevated temperature and then cooled while confined againstexpansion, the base of the groove being deeper at one end than at theother and wider than the seal ring, and said seal ring being relativelyloosely received in the deeper end of the groove and relatively tightlyengaged between the base of the groove and said other member whenreceived in the shallower end of the groove, so that said ring may bearranged in said deeper end during raising of the temperature of saidring to said level and then caused to move into said shallower end whenthe ring is cooled.

5. Apparatus of the character defined in claim 4, wherein the base ofthe groove is conical.

1. A valve, comprising a metallic valve body having a flowwaytherethrough, a closure member mounted within the body for movementbetween positions opening and closing the flowway, an annular valve seatmounted within the flowway on one side of the closure member, a grooveabout one of the flowway and valve seat opposite the annular surface ofthe other of said flowway and valve seat, and a ring within the groovefor sealing between the flowway and valve seat, said ring being formedof a material which reforms into different shape if, when raised to anelevated temperature and then cooled to ambient temperature, it isconfined againSt expansion, the base of the groove being deeper at oneend than at the other and wider than the seal ring, and said ring beingrelatively loosely received in the deeper end of the groove andrelatively tightly engaged between the base of the groove and saidannular surface when received in the shallower end of the groove, sothat said ring may be arranged in said deeper end when said temperatureis raised to said elevated level and then caused to move into saidshallower end when said ring is cooled to ambient temperature.
 2. Avalve of the character defined in claim 1, wherein said valve bodyincludes separate portions which are welded together at a location nearsaid ring.
 3. A valve of the character defined in claim 2, wherein saidvalve body includes a central portion in which the closure member ismounted and another portion welded to and extending from one side of thecentral portion, and said valve seat is mounted within a recess in theother body portion.
 4. Apparatus comprising a first member receivedconcentrically within a second member, one of said members having agroove there about facing the other member, and a seal ring within thegroove which is formed of a material such as Teflon which reforms into adifferent shape if raised to an elevated temperature and then cooledwhile confined against expansion, the base of the groove being deeper atone end than at the other and wider than the seal ring, and said sealring being relatively loosely received in the deeper end of the grooveand relatively tightly engaged between the base of the groove and saidother member when received in the shallower end of the groove, so thatsaid ring may be arranged in said deeper end during raising of thetemperature of said ring to said level and then caused to move into saidshallower end when the ring is cooled.
 5. Apparatus of the characterdefined in claim 4, wherein the base of the groove is conical.